1. Field of the Invention
This invention relates to a nitrile resin composition. More specifically, the present invention pertains to a nitrile resin composition which has excellent transparency, antistatic property and practical physical properties and is suitably used as a material which can prevent the buildup of static electricity in various parts of electronics products, household electric appliances and office automation apparatuses, and various cases of semiconductor-wafer-related products, IC-related products, and mask/reticule-related products, liquid-crystal-display-related products.
2. Description of the Related Art
General-purpose resins such as styrene resin and acrylic resin are frequently used in household electric appliances and office automation apparatuses because of their excellent transparency and rigidity. These resins are however accompanied with the problems that since they have a large surface resistivity and easily build up static electricity by friction, contact or the like, they adsorb dust, which not only impairs the appearance but also presumably causes electrostatic breakdown of IC or the like.
With a view to imparting such a resin with antistatic properties, it is the common practice to knead in it a low-molecular-weight surfactant as an antistatic agent or apply such a surfactant on the surface of a formed or molded product, thereby lowering the surface resistivity. When the antistatic agent is kneaded in a resin, however, its antistatic effects last only while it exists on the surface of the molded or formed product, but tends to be removed easily from the surface by washing or wiping with a cloth or the like, which makes it difficult to impart the surface with long-lasting antistatic properties.
In addition, in order to impart the surface with a predetermined degree of antistatic properties, a comparatively large amount of the antistatic agent should be kneaded or applied, which becomes a cause for making the surface of the molded or formed product sticky.
As a process which can overcome the above-described problems and impart the surface with long-lasting antistatic properties, proposed are a method (in Japanese Patent Application Laid-Open Nos. SHO 55-36237 and SHO 63-63739) of adding, to an acrylic resin, a vinyl copolymer having a polyethylene chain with a sulfonate group, carboxylate group or a quaternary ammonium salt group introduced therein; and a resin composition (in Japanese Patent Application Laid-Open No. SHO 62-241945) of a specific polyether ester amide elastomer, graft copolymer and a modified vinyl polymer containing a carboxyl group. These methods use the polymers which are not easily commercially available so that the production cost becomes high. The former method of adding the above-described the copolymer to an acrylic resin has the problem of impairing transparency and heat resistance which are characteristics of the acrylic resin.
In Japanese Patent Application Laid-Open No. HEI 8-253640, a resin composition comprising a polyether ester amide and a thermoplastic resin such as styrene resin is disclosed. Since this resin composition contains as main components a styrene resin and alkyl (meth)acrylate resin, it is inferior in mechanical properties, particularly impact resistance. Although having improved antistatic properties, the molded or formed product from the resin composition is presumed to have poor appearance due to a peeling phenomenon, because no limitation is imposed on the molecular weight and melt viscosity of the resin and melt viscosity of the polyether ester amide. Therefore, the above-described resin composition is not always satisfactory.
Nitrile resins are excellent in transparency, mechanical properties and dustproofness. They are therefore used frequently as a material for a carrier of electronic parts, however, their antistatic properties are not sufficient. There is accordingly a demand for the development of a material which is transparent and has excellent antistatic properties.
An object of the present invention is to provide a resin composition of polyether-ester-amide and nitrile resin having excellent transparency, antistatic properties and practical physical properties.